Memory devices have been widely used in electronic systems for data storage. They can be divided into two categories: volatile memory device and non-volatile memory device. A volatile memory device requires power to maintain the stored information. In contrast, a non-volatile memory device retains its information even when the power is turned off. Like other types of semiconductor devices, as the sizes become smaller, difficulties on manufacture may emerge. For example, in the manufacture of a static random-access memory (SRAM) of the 14 nm node or an even smaller node, the loss at the edge of a memory array region due to the boundary effect of the mask may be a critical problem.